Setup to reproduce ktor + exposed + hikaricp test failure

There seems to be some issue when combining Ktor's testApplication with Kotlin Exposed's "suspending transactions" and HikariCP. It seems that the DB connections are sometimes leaking between the tests, i.e. test X uses a DB connection from a preceding test, which is then closed. Because this behavior is flaky / not always occurring I created 10 identical tests inside the same class, to increase the probability of a test failure.

The problem does not seem to occur if I perform similar tests without testApplication. See DbConnectionWithoutKtor.kt for these tests. Moreover, DbConnectionWithKtor.kt does not seem to fail with regular Exposed transaction (not suspending fun).

Steps to reproduce:

• Run DbConnectionWithKtorTest.kt or mvn test -Dtest=DbConnectionWithKtorTest until it fails. Usually it fails within 5 runs.

Snippet of test failure:

Also see error-test-run-complete.txt for the log of a failed test run, and/or error-test-run-specific-test.txt for the log of specific test that failed